I don't believe the dealer

 

What part do you not believe? I have 3 trade in offers in the last 30 days. $70k is the top offer for a 2013 Vantage Roadster. Hard to believe for such a nice car considering a 718 Boxster S is $82K with a rubber dash.

 

that seems so low usually depreciation is like 10% a year so after 5 its around 50% of original sticker, right?

 

The more expensive the car, the steeper the initial depreciation is sometimes.

Remember, Aston Martin dealers don't sell most of their stuff at the sticker price in the first place, so the initial sales price is already down from the sticker price.

Then, you take two cars, one highly optioned and the other not, and they're going to depreciate to close to the same value -- the options depreciate out very quickly, particularly if they are cosmetic things like different-color brake calipers. A buyer even a couple of years down the road doesn't care that those brake calipers cost an extra $1595 to have in a different color -- that sort of option depreciates by something like 90% the second the car is driven off the lot.